The present invention relates to can making and, more specifically, to testing of cans for leaks or similar defects.
In the manufacture of cans and can end closures, it is desirable to test the finished product prior to shipment. This may be accomplished by pressurizing the container and then measuring the pressure after a suitable time lapse. If the initial pressure has decreased, indicating the presence of a leak, the can may be rejected. Alternatively, the pressurized can may be placed in a sealed chamber which is initially at a predetermined pressure below the initial pressure of the can. If the can is defective, the pressure within the chamber will increase as the pressurant passes from the can into the chamber.
Performace of tests of the type just described has been automated to permit testing of all units of the product, rather than mere testing of random samples. The test equipment is designed to reject any unit which permits the loss of approximately 9 c.c. of air, pressurized to 10 p.s.i.g., within a 10 second interval. At present, calibration of the equipment to verify that defective units are indeed being rejected, is a time consuming, and hence costly, process.
It is therefore a primary object of the present invention to provide an improved test fixture for rapidly and reliably verifying the proper operation of can testing equipment.
This is accomplished by providing a test unit having a simulated leak permitting a loss of pressurant slightly in excess of the predetermined maximum allowable, whereby rejection of the test unit indicates proper performance of the test equipment.
It is a further object to provide a method for producing the aforementioned test fixture.
With the above and other objects in view that will hereinafter appear, the nature of the invention will be more readily understood by reference to the following description, the appended claims and the several views illustrated in the accompanying drawings.